The present invention relates to speech recognition and more particularly to methods for preselecting or screening candidate models for accurate matching with an unknown speech segment.
In order to be useful for many user applications, a speech recognition system should be capable of recognizing a large vocabulary of words. Distinguishing between words in a large vocabulary system requires that the system be capable of a high degree of accuracy in comparing an unknown speech segment with the models representing the vocabulary words. As is understood, high accuracy carries with it a substantial cost in terms of computational complexity and, while various techniques have been evolving for efficiently doing the necessary calculations, it has been becoming increasingly necessary to provide some method of screening or preselecting candidate models prior to applying a high precision matching algorithm. The present invention utilizes several novel methods to effect preselection of candidate models in such a way that unlikely candidates are quickly weeded out with minimal risk of eliminating the best matches.